SAN FRANCISCO -- In perhaps the clearest sign yet that it has its eyes fixed on going public, file-sharing startup Dropbox on Thursday said it has hired the former head of Motorola Mobility to be its first chief operating officer.

Dropbox CEO Drew Houston, in an emailed statement, said of Dennis Woodside: "I can't imagine a better person to help us bring Dropbox to global scale."

Woodside was a longtime Google executive who was put in charge of Motorola Mobility after the Mountain View search giant bought the mobile phone maker in 2011. When Google last month announced it would sell the unprofitable division to Chinese computer and smartphone maker Lenovo, officials said Woodside would stay to guide the transition.

But in Dropbox, he may have found an opportunity too tempting to pass up. The San Francisco company says 200 million people use its file-sharing and storage services. Last month, it reportedly raised $250 million from investment giant BlackRock in a deal that pegged the startup's value at $10 billion.

Another Dropbox investor praised the Woodside hire Thursday. "Dropbox has been amazing for a long time at bringing in top talent, and I'd say this is just an exclamation point on that," said Michael Moe, co-founder of GSV Capital. His investment firm owns 1.3 million shares of Dropbox, which it acquired on secondary markets from company insiders.